EP0110872B1 - Hypsomètre - Google Patents

Hypsomètre Download PDF

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Publication number
EP0110872B1
EP0110872B1 EP19830890217 EP83890217A EP0110872B1 EP 0110872 B1 EP0110872 B1 EP 0110872B1 EP 19830890217 EP19830890217 EP 19830890217 EP 83890217 A EP83890217 A EP 83890217A EP 0110872 B1 EP0110872 B1 EP 0110872B1
Authority
EP
European Patent Office
Prior art keywords
wick
thermistor
liquid
boiling
hypsometer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19830890217
Other languages
German (de)
English (en)
Other versions
EP0110872A3 (en
EP0110872A2 (fr
Inventor
Franz Aigner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Andritz Hydro GmbH Austria
Original Assignee
Andritz Hydro GmbH Austria
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Andritz Hydro GmbH Austria filed Critical Andritz Hydro GmbH Austria
Publication of EP0110872A2 publication Critical patent/EP0110872A2/fr
Publication of EP0110872A3 publication Critical patent/EP0110872A3/de
Application granted granted Critical
Publication of EP0110872B1 publication Critical patent/EP0110872B1/fr
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
    • G01L11/002—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by thermal means, e.g. hypsometer

Definitions

  • the invention relates to a hypsometer for measuring the ambient pressure, in particular the air pressure, which consists of an optionally heated container, which is partially filled with liquid, in which a wick extending to the bottom of the container and consisting of absorbent material is arranged, which is connected to the Air surrounding end is provided with a thermistor covered by the wick and wherein the wick is surrounded by a cladding tube, the lower end of which is provided with an opening.
  • Hypsometers are devices for measuring air pressure. This makes use of the physical fact that the boiling point of a liquid changes with the ambient pressure. Therefore, if the vapor pressure curve of the hypsometer fluid is known and the boiling temperature is measured with sufficient accuracy, the ambient pressure, in particular air pressure, can be calculated.
  • the pressure measurement is thus traced back to a temperature measurement, and this in turn if, for example, as a temperature sensor a thermistor is used on a resistance measurement.
  • the use of the hypsometer has been in use in meteorological radio probes for a long time.
  • the resolution of the pressure measurement is therefore better at high altitudes, i.e. at low pressure and thus also lower boiling temperature, than near the ground.
  • Height determinations from the measured air pressure can therefore be expected to be very accurate when using the hypsometer, whereas height determination with the use of an aneroid can becomes more and more problematic with increasing height because the can registers pressure changes almost linearly and the height difference per pressure unit increases logarithmically with height.
  • a hypsometer as described below is known from AT-PS No. 354 785.
  • the thermistor is usually located in a wick made of an absorbent material, such as cotton, blotting paper or the like, which extends with its lower end to the bottom of the container.
  • the liquid that is sucked up boils in the wick, bringing the thermistor to the boiling point.
  • the part of the wick, which is located below the thermistor is sometimes provided with a covering which, apart from the boiling zone, only leaves the base of the wick exposed. This ensures that the liquid does not evaporate on its way from the lower end of the wick to the thermistor.
  • the size of the free surface of the wick available as a boiling surface is not without an influence on the measuring accuracy. With a large surface area and a relatively high ambient temperature, the liquid evaporates faster than it is sucked in through the wick, but this would mean that part of the boiling surface would not be wetted by the boiling liquid and it is therefore uncertain whether the thermistor is entirely in the boiling liquid. In this case the thermistor would register a temperature higher than the boiling point of the liquid. If the ambient temperature is low and the heating is insufficient, however, the boiling process of the liquid can cool down too much and thus stop itself. If enough outside air can now reach the boiling surface, the liquid will no longer boil on the surface of the boiling area, but will evaporate and cool down, as does the thermistor.
  • the Thermisor registers a lower temperature than the boiling point of the liquid, which means that the boiling area of the wick should be as small as possible and that the ambient temperature and the outside air must be kept far away from the boiling zone.
  • the size of the boiling surface is largely determined by the type and shape of the wick and the size of the thermistor. With a wick that is ideally adapted to the thermistor, only the thermistor determines the size of the boiling surface.
  • Another disadvantage is that the boiling temperature near the bottom makes the resolution of the pressure measurement insufficient.
  • the resistance can be increased by a suitable material composition of the thermistor, but the exact predictability of the thermistor suffers as a result.
  • Another difficulty is the impossibility of air access to completely prevent the boiling surface, since pressure measurement is only possible at all if the pressure is completely equalized.
  • the effects of air access mainly affect measurements near the ground. With the low air density at a higher altitude, there is only a slight evaporation of the frigens and the cooling remains negligibly small.
  • the arrangement of the cladding tube which is known per se, prevents most of the liquid from evaporating even before it has reached the height of the thermistor, but the improvement associated with this is still not sufficient. Attaching a heat-insulating cap around the evaporation area of the hypsometer is also not sufficient.
  • the object of the invention is to avoid the above disadvantages and to increase the accuracy of the hypsometer in the static range to such an extent that the remaining residual error when used in radio probes can be neglected.
  • the hypsometer shown at the outset is characterized in that the end of the wick protruding into the liquid is free from the cladding tube and the end of the wick provided with the thermistor is encased in cladding tube, and in that the cladding tube consists of poorly heat-conducting material.
  • the advantage of the invention is that the boiling surface is reduced to the surface of the short piece of wick protruding from the cladding tube, when the cladding tube closes with the upper end of the wick, only the clear cross section of the cladding tube remains as the boiling surface. This reduces the amount of liquid evaporating and the wick can always draw in enough liquid.
  • the inside pressure is the same as the outside pressure.
  • the liquid can therefore never be warmer than the boiling temperature corresponding to the pressure. Otherwise, it would start to boil immediately and cool down to boiling temperature.
  • the resulting steam is condensed again when climbing up in the cladding tube due to the colder liquid that has already been sucked in higher, so that the exact boiling temperature is set overall.
  • the cladding tube consists of poorly heat-conducting material, there is practically no temperature exchange through the tube wall. This has a favorable effect even at low temperatures, because the liquid reaches the thermistor at the boiling temperature and the area where air can wick and the liquid can evaporate is very small and high above the thermistor in the direction of movement of the liquid . As a result, the correct temperature is supplied to the thermistor by the sucked-in liquid faster than the heat is removed by the evaporation surface.
  • the free length of the end of the wick provided with the thermistor can be changed within certain limits, the region of the thermistor being predominantly covered. This allows the hypsometer to be better adapted to certain tasks.
  • the thermistor 1 is closely enclosed by a wick 2.
  • the contacted ends 6 of the thermistor 1 exit through the wick 2.
  • the wick 2 is surrounded by the cladding tube 3.
  • the liquid 5 sucked up by the wick 2 due to its capillary action from the storage container 4 comes up and the thermistor 1 is therefore completely surrounded by the boiling liquid.
  • the container 4 can be closed with a heat-insulating cap 7 which has a pressure compensation opening 8.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)

Claims (3)

1. Hypsomètre pour la mesure de la pression ambiante, en particulier de la pression de l'air, constitué par un récipient (4) éventuellement chauffé qui est partiellement rempli de liquide, dans lequel est disposée une mèche (2) en matière absorbante qui plonge jusqu'au fond du récipient, qui est munie à l'extrémité entourée d'air d'une thermistance (1) elle-même enveloppée par la mèche (2), la mèche (2) étant entourée d'un tube gaine (3) dont l'extrémité inférieure est munie d'une ouverture, caractérisé en ce que l'extrémité de la mèche (2) qui plonge dans le liquide (5) est dégagée du tube gaine (3), l'extrémité de la mèche (2) qui est munie de la thermistance (1) étant entourée par le tube gaine (3), et en ce que le tube gaine (3) est fait d'une matière mauvaise conductrice de la chaleur.
2. Hypsomètre selon la revendication 1, caractérisé en ce que la longueur libre de l'extrémité de la mèche (2) qui est munie de la thermistance (1), peut être modifiée dans certaines limites, la région de la thermistance (1) étant enveloppée en majeure partie.
3. Hypsomètre selon la revendication 1, caractérisé en ce que l'extrémité de la mèche (2) qui est munie de la thermistance (1), est entourée du tube gaine (3) jusqu'au bord supérieur de la mèche.
EP19830890217 1982-12-06 1983-11-29 Hypsomètre Expired EP0110872B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT0441982A AT381170B (de) 1982-12-06 1982-12-06 Hypsometer
AT4419/82 1982-12-06

Publications (3)

Publication Number Publication Date
EP0110872A2 EP0110872A2 (fr) 1984-06-13
EP0110872A3 EP0110872A3 (en) 1985-07-10
EP0110872B1 true EP0110872B1 (fr) 1988-05-11

Family

ID=3563754

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19830890217 Expired EP0110872B1 (fr) 1982-12-06 1983-11-29 Hypsomètre

Country Status (4)

Country Link
EP (1) EP0110872B1 (fr)
AT (1) AT381170B (fr)
DE (1) DE3376584D1 (fr)
FI (1) FI74141C (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3942343A1 (de) * 1989-12-21 1991-06-27 Bosch Gmbh Robert Verfahren zur bestimmung der druckaenderung

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB842037A (en) * 1957-12-17 1960-07-20 Victory Engineering Corp Improvements in and relating to pressure measuring apparatus
US3276262A (en) * 1964-07-21 1966-10-04 Victory Engineering Corp Long operating hypsometer structure
AT354785B (de) * 1978-07-14 1980-01-25 Gruber Anton Einrichtung zur hypsometrischen luftdruck- messung

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3942343A1 (de) * 1989-12-21 1991-06-27 Bosch Gmbh Robert Verfahren zur bestimmung der druckaenderung

Also Published As

Publication number Publication date
FI74141C (fi) 1987-12-10
ATA441982A (de) 1986-01-15
EP0110872A3 (en) 1985-07-10
EP0110872A2 (fr) 1984-06-13
AT381170B (de) 1986-09-10
FI834427A0 (fi) 1983-12-02
FI74141B (fi) 1987-08-31
FI834427A (fi) 1984-06-07
DE3376584D1 (de) 1988-06-16

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